Thailand is poised to overhaul its liberal visa rules as the government ramps up a crackdown on foreigners who illegally run businesses or commit transnational crimes.

Possible measures include reducing the 60-day visa-free stay for tourists to 30 days and reviewing the criteria for categories, including investment, long-term stay, student and digital nomad visas, according to officials. Visitors from 93 countries currently are eligible for the 60-day waiver.

Prime Minister Anutin Charnvirakul had ordered the setting up of a working group to review the rules, government spokeswoman Rachada Dhnadirek said in a statement.

Anutin visited the tourist hotspot Phuket earlier this week and pledged no tolerance for foreign “thugs” who encroach on public beaches to run illegal businesses and threaten locals. The recent arrest of a Chinese national with a cache of arms in Pattaya, another popular tourist destination, has heightened national security concerns.

The review is a response to long-standing complaints from local businesses – especially in areas popular with foreign tourists – that their livelihoods are being threatened by visitors who misuse visas to engage in prohibited activities.

Anutin, whose conservative Bhumjaithai party leads the ruling coalition, told reporters this week that he was not looking to completely scrap free visas as Thailand could still generate enormous revenue from foreign tourists entering the country legally.